The striate cortex of one hemisphere of a rhesus monkey is removed surgically under direct vision. The monkeys are allowed to recover from the effects of surgery in a normally lit environment. The monkeys are then trained on a series of tasks requiring visual perception and visually-guided eye movements. They are then prepared for chronic neurophysiological recording and for eye position recording. The activity of single neurons in the posterior parietal cortex both ipsilateral and contralateral to the lesion, is studied. The monkey's oculomotor capacity is studied quantitatively. Preliminary results indicate that the great bulk of the parietal cortex has its visual responsiveness to stimuli contralateral to the damaged hemisphere eliminated. The animals can make normal saccadic eye movements into the contralateral field and normal pursuit movements. However, they cannot make normal pursuit movements when the stimulus is artificially maintained in the visual field contralateral to the lesions. This indicates that visual activity in the posterior parietal cortex is partially dependent upon an intact visual cortex as is normal pursuit movement.